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Changing the G81 code  

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dennis.p8
(@dennis-p8)
Eminent Member
Changing the G81 code

Hi all,

Today I am trying to adjust my bed level to make it almost zero on every nine measured points using the following guide:

https://github.com/PrusaOwners/prusaowners/wiki/Bed_Leveling_without_Wave_Springs

Everything is going well till the point I need to have all points relative fixed to the center, which looks like this when the Probe has done it measuring:

The guide then says I have to change the G81 code with the following:

From this point I don't know what to do. Where can I change the G81 code? The guide is not clear for me (or I am just a programming noob 😀 ). Can anyone help me where to change the G81 code?

Thanks in advance!

Posted : 02/12/2018 12:50 pm
JBinFL
(@jbinfl)
Reputable Member
Re: Changing the G81 code

Dennis:

An alternative approach which may not fully answer your question, but since you indicate you are a programming noob it might be helpful... From the link you posted:

"Note this is using the firmware tweak below, making all numbers center-relative. If not using the firmware tweak, subtract the number of the center point from the others. You only care about the perimeter points that I've highlighted above

....

(remember that if not using the firmware tweak below, you'll need to subtract the value of the center point, in order to get the relative values) Ignore all the fictional numbers, especially since the algorithm used to derive them seems utterly broken (I think they're trying to do a curve fit, but with a poor choice of params, though I haven't actually spent the time to look at the algorithm in the firmware)."

You could just use Excel and subtract the center point number from the other 8 points (because center point - center point = 0). This will get you to the relative values of the other numbers to the center point without having to compile code and potentially mess something up.

Just a thought unless you actually want to change the G81 code... BTW, when i previously went to that post to do this on my own, I could not see anything highlighted in the post that you linked so i did not know what should be changed in any event...

Strange women, laying in ponds, distributing swords, is hardly a basis for a system of governance!

Posted : 02/12/2018 3:22 pm
dennis.p8
(@dennis-p8)
Eminent Member
Topic starter answered:
Re: Changing the G81 code


Dennis:

An alternative approach since you indicate you are a programming noob... From the link you posted:

"Note this is using the firmware tweak below, making all numbers center-relative. If not using the firmware tweak, subtract the number of the center point from the others. You only care about the perimeter points that I've highlighted above

....

(remember that if not using the firmware tweak below, you'll need to subtract the value of the center point, in order to get the relative values) Ignore all the fictional numbers, especially since the algorithm used to derive them seems utterly broken (I think they're trying to do a curve fit, but with a poor choice of params, though I haven't actually spent the time to look at the algorithm in the firmware)."

You could just use Excel and subtract the center point number from the other 8 points (because center point - center point = 0). This will get you to the relative values of the other numbers to the center point without having to compile code and potentially mess something up.

Just a thought unless you actually want to change the G81 code... BTW, when i previously went to that post to do this on my own, I could not see anything highlighted in the post that you linked so i did not know what should be changed in any event...

Hmm yea I have seen I can also substract. Will try that now, as I read it is pretty hard to change it I guess.

Posted : 02/12/2018 3:40 pm
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